Clarification process

ABSTRACT

A clarification process using a water-soluble lignin-di-epoxide composition as a flocculating agent is described. The lignin-di-epoxide compositions are prepared by cross-linking of lignin with a di-epoxide.

This is a division of application Ser. No. 305,821 filed on Nov. 13,1972 Now U.S. Pat. No. 3,857,830.

This application relates to a clarifying process using novel lignincompounds as flocculating agents. More particularly, it pertains tousing high molecular weight lignin compositions prepared bycross-linking of lignin with a di-epoxide as coagulants or flocculatingagents.

One of the major contributors to pollution of streams and waterways isthe effluent discharged into the waterways without proper treatment toremove the fine, colloidal particles of solids dispersed in theeffluent. While the large particles may be settled out withoutdifficulty, the fine solids do not settle and have to be treated with aflocculating agent or coagulant to coagulate or aggregate the particlesbefore settling. Multivalent salts such as ferric chloride and aluminumsulfate are commonly used for particular systems but are of limitedeffectiveness even in the systems used. The more effective organicpolyelectrolytes are relatively expensive and cannot be economicallyused in many applications.

The surface active properties of lignins and lignosulfonates have longbeen recognized, and these products have been used as dispersing andflocculating agents. While it was known for a number of years that highmolecular weight lignin and lignosulfonate, such as obtained byfractionation or polymerization of pulping liquors, function asflocculating agents, these materials do not have sufficienteffectiveness for commercial acceptance and are suggested for use mainlyas flocculating aids in conjunction with other flocculating agents.Polymerization of lignosulfonates and the reaction of lignins withaldehydes and other reactants, such as disclosed in U.S. Pat. Nos.3,470,148 and 3,600,308, have not improved the effectiveness of thesematerials to make them commercially attractive.

It is therefore the object of this invention to provide a clarificationprocess for flocculation of solids suspended in an aqueous medium usingimproved flocculating agents prepared from lignin and lignosulfonates. Afurther object is to provide watersoluble lignin and lignosulfonatecompositions which are effective flocculating agents. A still furtherobject is to provide a method for the preparation of these compositions.

The above and other objects are obtained according to this invention byusing as a flocculating agent a water-soluble lignindi-epoxide reactionproduct obtained by reacting a lignin with a long chain, terminaldi-epoxide having a molecular weight in the range of from 120 to 1800 tothe extent that the phenolic hydroxyl content of the lignin has beenreduced from about 40% to 95%. By reacting the lignin with a limitedamount of epoxide under controlled conditions, cross-linking or bridgingof the lignin by long chains is obtained resulting in formation ofmolecules having large entities held together at a distance from eachother by non-rigid, flexible bonding. These products when dissolved inaqueous medium form loosely bound, flexible molecules having increasedarea for adsorption or entrapment of fine solid or colloidal particlesin the solution or suspension to result in the flocculation of theseparticles.

While the lignin may be reacted with the di-epoxide by the various knownmethods, it is essential that the reaction be carried out undercontrolled alkaline conditions to prevent the lignin from reacting withthe di-epoxide to the extent that the reaction product becomeswater-insoluble. The preferred method for cross-linking or bridging ofthe lignin molecules with the epoxide is to react the di-epoxide withthe lignin in an aqueous lignin solution under alkaline conditions. Thedi-epoxides generally have limited solubility in water and areintermixed with the aqueous lignin solution to form a two-phase systemor an emulsion. With the more viscous or solid di-epoxides, thedi-epoxide may be dissolved in a water-immiscible organic solvent priorto intermixing with the lignin solution. Thus, the initial reaction ofthe lignin with the di-epoxide is effected at the interface of thetwo-phase system. Upon having one of the epoxides reacted with thelignin, the epoxide-reacted lignin generally remains soluble in theaqueous phase where the unreacted epoxy group then further reacts withlignin in the aqueous solution. The aqueous solution contains a highratio of lignin to epoxide to effect the cross-linking. By the aboveprocedure, the extent of reaction between the lignin and di-epoxide canbe controlled to obtain the desired bridging or cross-linking withoutthe reaction proceeding to insolubility. The reaction rate is controlledsuch that after the desired extent of reaction between the lignin andthe di-epoxide is obtained, unreacted epoxide may be recovered from thereaction mixture. The reaction may also be effected in an alkaline,aqueous medium by using a water-miscible solvent for the epoxide, suchas dioxane or a ketone or ether. The bridging or cross-linking reactionbetween the di-epoxide and the lignin is believed to be between thehydrogen of the phenolic hydroxyl radicals of the lignin and the epoxygroup of the di-epoxide. The epoxide ring is opened with the ligninbeing attached to one of the carbon atoms of the ring through an etherlinkage with the formation of a hydroxyl group on the second atom.

When the reaction is carried out with the lignin and the diepoxide in anorganic solvent, solvents such as formamide and tetrahydrofuran may beused. Since there are only a limited number of organic solvents,unreactive with the di-epoxides, for alkali and alkaline earth metalsalts of lignin, it may be convenient to convert the lignosulfonate toan amine salt, in a manner similar to that disclosed in U.S. Pat. No.3,578,651, prior to reaction with the di-epoxide. The alkyl ammoniumlignosulfonates are more soluble in a number of organic solvents.Pyridine, polychlorinated and brominated hydrocarbon solvents of from 1to 3 carbon atoms such as chloroform, dichloromethane, di- ortrichloroethane, trichloroethylene, perchloroethylene and thehalogenated propanes may be used. Most of the trialkyl ammoniumlignosulfonate salts and the di-epoxides are sufficiently soluble inthese solvents to effect the reaction. Other solvents which may be usedare dimethylformamide and ethers such as alicyclic ethers of from 4 to 5carbon atoms as dioxane, tetrahydrofuran, and tdtrahydropyran, glycoldiethers having from 4 to 10 carbon atoms, and phenolic ethers such asanisole and phenetole. The reaction is carried out in presence of a basewhich generally may be a tertiary organic amine such as pyridine, ordimethylbenzylamine or other base. An inorganic base such as sodiumhydroxide or potassium hydroxide may also be used by being dispersedwithin the solvent. Generally, the solvent may contain a sufficientamount of moisture to maintain the desired alkaline conditions.

After the reaction, the ammonium salt can be converted to the sodium orcalcium salt or any other metal salt desired prior to use as aflocculating agent.

Lignin is a polymeric substance of substituted aromatics found in plantand vegetable tissue associated with cellulose and other plantconstituents. In the pulp and paper industry, lignincontaining materialssuch as wood, straw, corn stalks, bagasse, and other vegetable and planttissues are processed to recover the cellulose or pulp. The residualpulping liquor containing the lignin as a by-product is thus one of themain sources of lignin. While there is some variation in the chemicalstructure of lignin, depending upon the plant from which lignin isobtained, the place where the plant is grown, and also upon the methodused in recovery or isolation of the lignin from the plant tissue; thebasic structure and properties of the lignin are similar; all containingthe phenolic hydroxyls through which the cross-linking or bridging iseffected. Thus, lignin obtained by any method or from any source may beused in this reaction as long as the lignin is in a form soluble in analkaline medium.

Since the lignin separated from the plant may be chemically alteredsomewhat from that found in the plant, the term "lignin", as usedherein, means the lignin product which is obtained upon separation fromthe cellulose or recovered from the plant. In the sulfate pulpingprocess, the lignocellulosic material is digested with a bisulfite orsulfite resulting in the sulfonation of the lignin. In other methods ofthe recovery or separation of the lignin from the plant, the lignin maynot be sulfonated but may be chemically altered somewhat in some othermanner. For example, in residual pulping liquors obtained in the sulfateand other alkaline pulping processes, the lignin is present as analkaline metal compound dissolved in the alkaline aqueous liquor."Hydrolysis lignin" obtained from the hydrolysis of lignocellulosicmaterials in manufacture of sugar is likewise altered somewhat from thatfound in the plant but may be relatively insoluble and thus may have tobe modified to solubilize the product before it can be used. Also, thelignin products such as a residual pulping liquor may be subjected tovarious treatments such as, for example, acid, alkaline or heattreatments or reacted with the other chemicals which may further altersomewhat the lignin constituents. The lignins remain operative as longas the treatment is not so severe as to destroy the basic polymericstructure or substantially reduce the phenolic hydroxyl content of thelignin.

The residual pulping liquors, or the lignin-containing product obtainedin the separation or recovery of lignin from the plant, may containother constituents besides the lignin. For example, in the sulfitepulping process, the spent sulfite liquor contains lignosulfonates,generally in an amount of 40 to 60 weight percent, which may be presentas salts of cations, such as magnesium, calcium, ammonium, sodium andother cation which may have been present during the sulfonation of thelignin with the remainder being carbohydrates and other organic andinorganic constituents dissolved in the liquor. Lignin products obtainedby other pulping processes may likewise contain other materials such ascarbohydrates, degradation products of carbohydrates, and resinousmaterials which are separated from the lignocellulosic materials withthe lignin. Lignin obtained by hydrolysis of lignocellulosic materialsmay not contain the carbohydrates but may contain resinous typematerials as well as other materials which are not removed by thehydrolysis. It is not necessary to separate the lignin-containingconstituents from the other constituents. The lignin product as obtainedcontaining all of the constituents may be used as such or subjected todifferent treatments such as alkaline, acid, or heat treatments as wellas reacted with chemicals to modify or remove some of the non-ligneousconstituents prior to reaction with the di-epoxide. The reaction of thedi-epoxide with the non-lignin constituents is not excessive and thepresence of the reaction products of these constituents does notmaterially effect the flocculating properties of the product. Thenon-lignin constituents are generally of relatively low molecular weightand can be easily removed from the final product after reaction, ifdesired. The lignin material may also be separated from the non-lignincontaining products prior to reaction with the di-epoxide, as well asafter reaction, using methods such as dialysis, gel permeation, andchemical precipitation as acid, calcium hydroxide, or amineprecipitation, or alcohol or solvent extraction, and other methods wellknown in the art for fractionation and recovery of organicpolyelectrolytes from lower molecular weight materials.

The di-epoxides reacted with the lignin are the "1,2-epoxides" or "alphaepoxides ", containing 2 alpha or terminal epoxy groups or oxiranerings. The epoxides must be relatively long chained epoxides having amolecular weight in the range of 120 to 1800, preferably in the range of250 to 800. The epoxides of molecular weight higher than 1800, whileoperative if reacted, are more difficult to react with the lignin to thenecessary extent to obtain an effective flocculating agent. Although thelinear, straightchained di-epoxides such as the diglycidyl ethers ofaliphatic polyols or polyalkylene glycols are preferred, the di-epoxidesdo not have to be the alkylene or oxyalkylene epoxides. The chain maycontain cyclic or aromatic groups such as, for example, substituted andnon-substituted cyclohexylene, phenylene, biphenylene, naphthylene andother arylene groups of up to 12 carbon atoms substituted in thealiphatic chain. The chain may also contain linking atoms such as oxygenin ether linkages, nitrogen, or sulfur atoms. When cyclic or aromaticgroups or other linking atoms are substituted in the chain, the oxiranegroups must be separated from the substituted group or linking atom byat least one carbon atom so that each epoxy group is on the end of analkylene group containing at least 3 carbon atoms to have the chainmaintain its linear characteristics. Further the chain may also containside chains as long as the side chains are of a size and number suchthat the epoxide does not lose its linear characteristics. The sidechains may be alkyl groups or substituted and non-substituted aromaticor cyclic groups including groups containing nitrogen or sulphur as wellas oxygen ether linkages. Generally the length of the side chains isless than 1/2 of the length of the main chain having the oxirane groups,and the total number of atoms of the side chains does not exceed thenumber of the atoms of the main chain. The nitrogen in the chains may bepresent as a tertiary amine radical or a quaternary ammonium salt withthe alkyl radicals on the nitrogen being of from 1 to 4 carbon atoms inlength with the total carbon atoms in the alkyl radicals on the nitrogennot exceeding about 8 carbon atoms. The most readily availabledi-epoxides are the diglycidyl ethers obtained by the reaction of theepichlorohydrin with polyhydric alcohols such as diols and polyalkyleneglycols. The nitrogen containing diepoxides may be similarly prepared byreaction of epichlorohydrin with amines, such as disclosed, for example,in U.S. Pat. Nos. 3,091,537 and 3,189,459. In addition, the di-epoxidesmay also be prepared by the peroxide route such as the reaction ofperacetic acid with di-olefins as well as dehydrohalogenation ofchloroacetyls and other methods known in the art.

Illustrative examples of the more readily available epoxides which maybe used are as follows:

1. Carbon-linked di-epoxides such as 1,2,7,8 -diepoxyoctane; 1,2,11,12-diepoxydodecane; 1,2,7,8 - diepoxy - 4 -methyloctane; 1,2,7,8 -diepoxy - 4,5 dimethyloctane; and other epoxides having a generalformula: ##EQU1##

Where R represents alkylene radicals having up to 18 carbon atoms,arylene or oxy-linked arylene radicals having up to 12 carbon atoms andR₁ represents hydrogen, phenyl or one or more alkyl radicals such thatthe total carbon atoms of R₁ does not exceed 1/2 of the carbon atoms ofthe chain containing the oxirane groups.

2. Diglycidyl ethers of aromatic and aliphatic polyols and such as 1,4 -butanediol; 1,8 - octanediol; 1,12 - dodecanediol; glycerol, sorbitol;Bisphenol A; 2,5 - bis (hydroxymethyl) tetrahydrofuran; 1,4 - bis[2-(4'-hydroxyphenyl) ethyl] benzene; and dihydroxynaphthalene; andepoxides having a general formula: ##EQU2##

Where R represents alkylene radicals having up to 18 carbon atoms,arylene or oxy-linked arylene radicals having up to 12 carbon atoms, andR₁ represents hydrogen, phenyl or one or more alkyl radicals such thatthe total carbon atoms of R₁ is less than 1/2 of the carbon atoms of thechain containing the oxirane groups. 3. Diglycidyl ethers ofpolyalkylene glycols such as polyethylene glycol and polypropyleneglycol and other epoxides having a general formula: ##EQU3##

Where "n" is a positive integer of from 2 to 20, R represents alkyleneradicals having from 2 to 4 carbon atoms, and R₁ represents hydrogen oralkyl radicals having from 1 to 2 carbon atoms with the total of R andR₁ not being greater than 4 carbon atoms. (4) Diglycidyl amines andamine salts such as N,N - bis (2,3 - epoxypropyl) methylamine; N,N - bis(2,3 - epoxypropyl) butylmethylammonium iodide; 1,4 - butylenebis [N -(2,3 epoxypropyl) - N,N - dimethylammonium iodide] and other epoxideshaving the general formula: ##EQU4## or ##EQU5##

Where m is a positive integer of from 2 to 5, n is a positive integerfrom 0 to 5, R₁, R₂, R₃, and R₄ represent alkyl radicals having from 1to 2 carbon atoms, and X represents bromide, iodide, arenesulfonate, oracetate ions.

The reaction of the lignin with the di-epoxide may be carried out byintermixing the di-epoxide with an alkaline aqueous lignin solution at apH of from 8 to 13, preferably 9 to 11. Alkali metal hydroxides andcarbonates, and alkaline earth metal hydroxides may be used for pHcontrol of the aqueous solution. The lignin is present as an alkali oralkaline earth metal salt in the solution and must be at an initialconcentration of at least 20 weight percent. Generally, a solutioncontaining initially from 20 to 50 weight percent of solids is used witha solution containing from 30 to 40 weight percent solids beingpreferred. Solutions above 45 percent concentration are relativelyviscous and more difficult to handle. In the preferred range, thesolutions are of sufficient concentration to obtain the desired reactionat a practical rate and at a sufficiently low viscosity to permitrelatively easy intermixing or emulsification with the diepoxide. As thereaction proceeds, the reaction mixture may have to be further diluted.For example, for most of the epoxides, the viscosity of the reactionmixture may increase rapidly as the di-epoxide reacts with the lignin toa point where the mixture gels. The reaction cannot be controlled underthese conditions and may result in the insolubilization of the product.To overcome this difficulty, additional water or solvent is generallyadded to the reaction mixture diluting the concentration of the reactionproduct to permit agitation and to further the desired reaction. Theaddition of water or solvent is made periodically to maintain thereaction mixture as concentrated as possible without gelling. Usually,the reaction is continued under viscous conditions, for example, at fromabout 5000 to 10000 centipoises under the temperature and shearconditions of the reaction. The reaction mixture generally isthixotropic so that the extent of dilution necessary will vary somewhatas to the type and extent of mixing employed in effecting the reaction.For example, when the reaction is carried out with a high degree ofmixing such as would be obtained in the blender, the reaction may becarried out under higher concentrations than when a relatively slowmixer is used. If the mixture is diluted too rapidly, the necessaryextent of cross-linking may not be obtained. By carrying out thereaction under high viscous conditions, the dilution may be made to theextent that the concentration of the final product may be reduced tobelow 20 percent and may be as low as 15 or so. However, usuallydilution to about 20 is sufficient in most cases to obtain the desiredextent of interaction without insolubilizing a large portion of thereaction product.

Generally, the epoxide is intermixed with the lignin solution in a ratioto obtain from about 0.5 to over 1.3 epoxy group for each phenolichydroxyl group on the lignin. The reaction is carried out at atemperature in the range of 50° to 220°C, preferably in the range of75°C to the reflux temperature of the mixture at atmospheric pressure,until from 40 to 95 percent of the phenolic hydroxyl groups on thelignin have been reacted. Products reacted with sufficient amount ofdi-epoxide to reduce the phenolic hydroxyl content of the lignin by from50 to 75 percent are preferred. The flocculating properties improve withincreased reaction with the di-epoxide until about 60 to 70 percent ofthe phenolic hydroxyl on the lignin has been reacted at which pointfurther reaction may not necessarily further improve the flocculatingproperties. When the amount of di-epoxide reacted exceeds the amountequivalent to satisfy the phenolic hydroxyls on the lignin, the productmay become insoluble even with dilution of the reaction mixture. Theinsoluble portion has limited effectiveness as a flocculating agent. Inthe reaction, the amount of the epoxide intermixed with the lignin canbe greater than that desired for the reaction. The reaction takes placeat a controlled rate so that all of the epoxide does not have to bereacted with the lignin and the unreacted reacted and unhydrolyzedepoxide can be recovered from the reaction mixture. Generally, theamount added is in a small excess of the amount of epoxide desired to bereacted with the lignin and the reaction carried out until most of thedi-epoxide has been reacted. The length of time required to react theepoxide depends upon the reaction conditions employed. For reactiontemperatures in the preferred range, generally a reaction time of from 1to 4 hours is sufficient. However, the reaction time may be varied from15 minutes to 24 hours or longer. At the preferred reaction temperature,generally products with optimum flocculating properties are obtainedwith a reaction time of from 1 to 4 hours. Prolonging the reaction timedoes not necessarily improve the effectiveness of the product. Forexample, a product reacted for 2 to 4 hours may have a settling time ofabout 60 seconds in flocculation of a dispersion which may increase toabout 80 seconds if the reaction time in preparation of the product isextended to 19 or 20 hours.

After the di-epoxide has been reacted with the lignin, the reactionmixture as obtained may be used as a flocculating agent. The reactionmixture may also be purified to recover the lignindi-epoxide product byseparating the unreacted di-epoxide or organic phase from the aqueousphase, especially if the recovery of the unreacted di-epoxide isdesired. The phases may be separated by intermixing a water-immiscibleorganic solvent with the reaction mixture to extract the di-epoxide andpermitting the phases to separate. However, the separation may be morerapidly effected by centrifuging the reaction mixture containing thediepoxide solvent. The aqueous phase thus obtained may be furtherprocessed to recover the epoxide-lignin reaction product from theremaining constituents, these constituents being mainly the diepoxidereaction products of the low molecular weight, non-ligneous constituentsof the lignin and inorganic salts. The high molecular weightconstituents can be recovered by the well known methods used forfractionation or recovery of high molecular weight polyelectrolytes. Theunreacted di-epoxide may be recovered from the organic phase and reused.

In using the lignin-di-epoxide composition, the same procedures andmethods employed for other polyelectrolytes or high molecular weightflocculating agents can be used. The products may be used by themselvesor in conjunction with other agents. They are effective in acid,neutral, or alkaline conditions for flocculation of relatively dilutedispersions containing less than 0.1% of solids to more concentrateddispersions containing from 4% to 10% or higher of solids and may beused in various amounts varying generally from less than 1 part permillion to 1000 parts per million depending upon the system beingtreated. For the flocculation of inorganic particles such as finelydispersed clay or sediment, an amount of from 10 to 30 parts per millionusually may be employed to obtain effective flocculation. The productsare also effective under acid conditions in flocculating finelydispersed organic material such as proteins. Generally the flocculatingtime does not decrease too rapidly when the amount of the flocculatingagent used is increased above about 10 to 30 parts per million. Forexample, a dispersion which may be flocculated in about 60 seconds with10 parts per million of the flocculating agent may have a floc time ofabout 50 to 55 seconds with 100 parts per million. A somewhat greatervariation in flocculating times than above may be obtained at the lowerlevels with the higher molecular weight flocculating agents cross-linkedwith the longer chained di-epoxides, such as diglycidyl ethers ofpolyalkylene glycols. For these products, the settling time may decreasefrom about 55 seconds to 35 seconds upon the increase of dosage from 10parts per million to 100 or more parts per million. Productscross-linked with the shorter di-epoxides are also more sensitive to thepH of the system being treated. For example a product prepared bycross-linking a lignosulfonate with a diglycidyl ether of polyethyleneglycol may be relatively independent of pH in the range of from about4.5 to 10 especially in the presence of electrolyte normally found inthe effluents or streams. However, lignosulfonate cross-linked with theshorter di-epoxides, such as the diglycidyl ether of the butanediol, maybe somewhat less effective under alkaline conditions than under acidconditions and higher dosages may be desirable.

The following examples further illustrate the invention.

EXAMPLE I

A fermented calcium base spent sulfite liquor was dialyzed as a 30weight percent aqueous solution against water using a polyvinyl alcoholmembrane. A dialyzate fraction containing about 74 weight percent of thespent sulfite liquor solids was obtained which was then base exchangedwith sodium sulfate to convert the calcium lignosulfonate dialyzate tothe sodium base and to precipitate the calcium sulfate. The sodium baselignosulfonate was adjusted to a pH of 11 by addition of sodiumhydroxide and spray dried. The spray dried sodium lignosulfonate, in anamount of 20.0 grams (97% solids), was dissolved in distilled water toobtain an aqueous solution having a pH of 9.4 containing about 39percent solids. The lignosulfonate solution was reacted with1,4-butanediol diglycidyl ether in a 250 milliliter, 3 neck, roundbottom flask. The 1,4-butanediol diglycidyl ether had a molecular weightof about 135 per epoxide and was dissolved in an amount of 2.4 grams in20 milliliters of trichloroethylene prior to intermixing with thelignosulfonate solution. The ratio of the epoxide groups to the phenolichydroxyl groups of the lignosulfonate was 0.8:1. The two-phase systemwas heated to reflux temperature with vigorous stirring of the reactionmixture to emulsify the trichloroethylene solution of the di-epoxidewith the aqueous lignosulfonate solution. The emulsion then wasmaintained at a temperature in a range of 75° to 80°C on a steam bathfor 4 hours, while being agitated, to obtain a gold-brown reactionmixture. The reaction mixture was centrifuged at 10,000 r.p.m. toseparate the organic and aqueous phases. The organic phase was dilutedwith 75 milliliters of acetone to precipitate any lignin product in theorganic layer or in the small amount of emulsion remaining intermixedwith the organic layer. The small amount of precipitate was removed byfiltration. The filtrate was dried over anhydrous magnesium sulfate andevaporated at 50°C at 25 millimeters of pressure absolute to recover theunreacted di-epoxide.

The aqueous layer recovered from the organic layer was dialyzedcontinuously against running water for 117 hours using a regeneratedcellulose dialysis casing. Evaporation of the dialyzate in a forced-airoven at 40°C gave 16.1 grams of dark, golden-brown product. Analyticaldata of the lignosulfonate prior to reaction with the di-epoxide and ofthe product are shown in the table below:

                   Sodium       Lignosulfonate                                                   Lignosulfonate                                                                             Di-epoxide                                        Analysis       Reactant     Product                                           ______________________________________                                        Methoxyl, wt % 10.7         12.1                                              Strong acids, meq/g                                                                          1.9          1.6                                               Weak acids, meq/g                                                                            1.2          0.47                                              Carboxylic acid, wt %                                                                        2.2          1.0                                               Phenolic hydroxyl, wt %                                                                      2.1          0.95                                              ______________________________________                                    

The methoxyl content of the lignosulfonate and the product wasdetermined by the Ziesel method as described in Organic Analysis by JohnMitchell, Jr., et al, Volume I, Page 93, Interscience, New York (1953).The phenolic hydroxyl content was determined by the procedure of OttoGoldschmid, "Determination of Phenolic Hydroxyl Content of LigninPreparations by Ultra-violet Spectrophotometry", Analytical Chemistry,26, p. 1421 (1954). The strong acid, weak acid, and the carboxylic acidcontent were determined by conductometric titration.

The lignosulfonate-di-epoxide composition was tested as a flocculatingagent in the flocculation of clay in an aqueous system at a pH of 5. Acommercially available low-yield clay (Panther Creek) was dispersed inwater to obtain a dispersion containing about 4 weight percent of clay.Sodium chloride was also added in an amount of about 1,000 parts permillion. The test was carried out by inverting and shaking 100milliliter samples of the clay suspension in a 100 milliliter graduatedcylinder and then noting the time taken for the boundary line of theclay to settle to half-volume or 50 milliliter mark on the cylinder. Thesettling time for the lignosulfonate-di-epoxide product was thusdetermined when the flocculating agent was added in an amount of about10 parts per million. The results obtained were compared to theflocculating time required for the clay to settle to the half-volumemark without the addition of the lignosulfonate. The results obtainedare shown in the table below.

    ______________________________________                                                        Amount      Settling Time                                     Sample          Added, p.p.m.                                                                             Secs.                                             ______________________________________                                        Blank           --          430                                               Lignosulfonate-di-epoxide                                                                     10           85                                               product                                                                       ______________________________________                                    

EXAMPLE II

A sodium lignosulfonate prepared from a fermented calcium base spentsulfite liquor in a manner similar to that described above was reactedwith 1,4-butanediol diglycidyl ether at various reaction times. Thelignosulfonate in an amount of 21 grams was dissolved in 30 millilitersof distilled water to obtain a lignosulfonate solution containing about40% solids. The solution was intermixed with 2.4 grams of 1,4-butanedioldiglycidyl ether which amount was the equivalent to 0.8 epoxy group foreach of the phenolic hydroxyl groups in the lignosulfonate solution. Inone of the samples, the di-epoxide was dissolved in 3 milliliters oftrichloroethylene prior to intermixing with the solution. The two-phasereaction mixture was heated on a steam bath and reacted at a temperaturein the range of 70° to 76°C for 4 hours while the reaction mixture oremulsion was continually stirred. Additional distilled water andtrichloroethylene were added periodically to the reaction mixture as thereaction proceeded to dilute the reaction mixture to maintain itstirrable. A total of 32 milliliters of additional water and 23milliliters of additional trichloroethylene was added. At the end of 4hours, the reaction mixture was cooled and the mixture was tested as aflocculating agent without the recovery of the lignosulfonate-di-epoxideproduct. The flocculation test was similar to that described above inExample I. The crude product was added to the 100 milliliters of claysuspension in an amount of about 2 to 3 drops which represented anaddition of the lignosulfonate-di-epoxide product in an amount of from10 to 20 parts per million. The settling time to settle the clay to ahalf-volume was 67 seconds.

The cooled reaction mixture was intermixed with 50 milliliters of etherto extract the unreacted di-epoxide and centrifuged to separate theaqueous phase from the organic phase. The organic phase was diluted withabout 100 milliliters of acetone to precipitate any lignin product fromthe organic phase and the small amount of emulsion dispersed in theorganic phase. The organic phase then was dried and upon evaporation 0.8gram of unreacted di-epoxide was recovered.

The aqueous layer was dialyzed continuously against running water in aregenerated cellulose casing, then air dried at 25°C to obtain 15.0grams of lignosulfonate-di-epoxide product. The di-epoxide product uponbeing tested as a flocculating agent in a manner described above at ausage of 10 parts per million had a settling time of 86 seconds.

A second run was made where the lignosulfonate was reacted with1,4-butanediol diglycidyl ether in a manner similar to the proceduredescribed above except that the 1,4-butanediol diglycidyl ether wasintermixed with the lignosulfonate solution directly without the use ofthe organic solvent. The reaction was carried out by heating thereaction mixture for 5 hours on a steam bath at a temperature of about70°C. At the end of 5 hours, approximately 62% of the phenolic hydroxylson the lignosulfonate had been reacted and the reaction mixture whentested as a flocculating agent had a flocculating time of 54 seconds.Upon ether extraction and centrifuging the reaction mixture, 0.3 gram ofunreacted diepoxide was recovered from the organic phase and afterdialysis 16.3 grams of the lignosulfonate-di-epoxide product wasrecovered from the aqueous phase. The purified product when tested as aflocculating agent at a procedure described in Example I gave aflocculation time of 80 seconds at a dosage of 10 parts per million.

Further, a third run was made similar to that described above whereinthe 1,4-butanediol diglycidyl ether was dissolved in 3 milliliters oftrichloroethylene and the reaction carried out for a total of 19.3hours. During the reaction, water was periodically added to a total of75 milliliters. No additional trichloroethylene was added. After thelignosulfonate solution was reacted with the trichloroethylene solutionof 1,4-butanediol diglycidyl ether for about 1.5 hours, a small sampleof the reaction mixture was withdrawn and tested as a flocculatingagent. The procedure used for testing the crude product was similar tothat described for testing the reaction mixture above utilizing about 2to 3 drops of the reaction mixture for 100 milliliters of the claysuspension. The flocculation time obtained was about 70 seconds. After areaction time of 3.5 hours, the flocculation time was 59 seconds. Uponcontinuing the reaction for a total period of 19.3 hours, theflocculation time for the reaction mixture was 78 seconds.

EXAMPLE III

A sodium lignosulfonate similar to that above was reacted withpolyethylene glycol diglycidyl ether. The polyethylene glycol diglycidylether had an average molecular weight of about 290 per epoxide.

The polyethylene glycol diglycidyl ether was reacted with thelignosulfonate solution in a manner described above wherein thedi-epoxide was dispersed in about 40 weight percent concentrationlignosulfonate solution without the use of any organic solvent. Thepolyethylene glycol diglycidyl ether was added in an amount to obtain aratio of 0.8 epoxy group for each phenolic hydroxyl of thelignosulfonate. The reaction mixture was heated and reacted on a steambath for about 4.1 hours at a temperature of 75° to 85°C. Water in atotal amount of about 149 milliliters was added periodically to thereaction mixture as the viscosity of the mixture increased upon thereaction of the lignosulfonate with the di-epoxide. The aqueous phasewas recovered by extraction and centrifugation, dialyzed, and dried inthe manner described above. The intrinsic viscosity of the product,determined in a 0.1 N sodium chloride solution, was 0.33 dlg⁻ ¹.

The product obtained was tested as a flocculating agent at severaldosage or usage levels using the procedure and clay suspension describedabove. Some flocculation tests were also made wherein the claysuspension was adjusted to a pH of 9 by addition of sodium hydroxide andthe sodium chloride content was increased to 4,000 parts per million.The results obtained are shown in the table below:

            Settling Time, Sec.                                                   Amount of                                                                     Product Clay Suspension                                                                             Clay Suspension                                         Added, p.p.m.                                                                         at pH 5       at pH 9                                                         1000 parts                                                                           4000 parts                                                                           1000 parts                                                                           4000 parts                                               NaCl   NaCl   NaCl   NaCl                                             __________________________________________________________________________     1      --     230    --     357                                              10      57     61     51     55                                               20      --     --     --     46                                               50      35     39     38     39                                               100     --     35     --     37                                               200     31     --     --     37                                               500     27     --     --     --                                               1000    31     --     --     --                                               __________________________________________________________________________

The product was also tested using 10,000 parts per million of theproduct in the suspension at a pH of 5 containing 1000 parts per millionof sodium chloride. Large flocs were formed upon addition of the largeamount of product which settled immediately to form a gelatinousprecipitate or sludge.

The flocculating time obtained by using 10 parts per million ofcommercially available polyelectrolyte, Separan AP 30, a partiallyhydrolyzed polyacrylamide manufactured by the Dow Chemical Company, gaveflocculating times of 18 and 19 seconds at pH of 5 and 9, respectively.

EXAMPLE IV

A sodium base lignosulfonate prepared from a fermented dialyzed calciumbase spent sulfite liquor was reacted with a polypropylene glycoldiglycidyl ether having an equivalent weight of about 190 per epoxide.

The sodium lignosulfonate in an amount of 20 grams was dissolved in 30milliliters of water in a 3-necked flask. To this solution, 3.4 grams ofpolypropylene glycol diglycidyl ether were added which gave a ratio of0.85 epoxy group for each phenolic hydroxyl of the lignin. The mixturewas reacted while being stirred under reflux at a temperature of about86°C. Water was periodically added to the reaction mixture after areaction time of about 13 minutes to dilute the reaction mixture tomaintain stirrability. A total of about 100 milliliters of water wasthus added during the 75 minute reaction time.

After the reaction, the reaction mixture was neutralized, extracted withether and centrifuged to separate the aqueous phase from the organicphase. The product was not dialyzed. About 0.1 gram of unreacted epoxidewas recovered. The cross-linked lignin product obtained was tested as aflocculating agent and the results obtained are shown in Table I below.

EXAMPLE V

A sodium base lignosulfonate similar to that of Example IV above wasreacted with a polypropylene glycol diglycidyl ether which had anequivalent weight of about 325 per epoxide. A ratio of about 0.85epoxide groups per phenolic hydroxyl of the lignin was obtained byadding 5.8 grams of the polypropylene glycol diglycidyl ether to asodium lignosulfonate solution obtained by dissolving 20 grams of thesodium lignosulfonate in 30 milliliters of water. The mixture wasreacted for 6.2 hours at a temperature of about 88°C. About 40milliliters of additional water was added during the reaction to dilutethe reaction mixture to maintain stirrability. After the reaction, thereaction mixture was neutralized, extracted with ether, and centrifugedto separate the organic phase from the aqueous phase containing thecross-linked lignin. Approximately 0.1 gram of the epoxide wasrecovered. The product obtained was tested as a flocculating agent andthe results are given in Table I below.

EXAMPLE VI

A sodium lignosulfonate prepared from a fermented, dialyzed calcium baseliquor was cross-linked with a diglycidyl ether prepared by reacting apolyethylene glycol having an average molecular weight of 600 withepichlorohydrin. The product had an average molecular weight of 715 perepoxide. The sodium base lignosulfonate in an amount of 10 grams wasdissolved in 15 milliliters of water to obtain a 40 weight percentsolution at pH 10.2. The solution was reacted with 8.1 grams of the highmolecular weight polyethylene glycol diglycidyl ether at a temperatureof about 86° for 3 hours and 10 minutes. A total of 80 milliliters ofadditional water was added during the reaction. After the reaction, thereaction mixture was neutralized, extracted with the ether, andcentrifuged. The cross-linked lignosulfonate was tested as aflocculating agent. The details and results are given in Table I below.

EXAMPLE VII

A sodium base lignosulfonate converted from a dialyzed, fermented,calcium base liquor similar to that of Example VI was cross-linked witha di-epoxide prepared by reacting 1,7-octadiene with chloroperoxybenzoicacid in chloroform. The product had an average molecular weight of about270 per epoxide.

The sodium lignosulfonate in an amount of 20 grams was dissolved in 30milliliters of water to obtain a solution at pH 10.2. To this solution,7.1 grams of the di-epoxide were added and the mixture reacted at atemperature of from 80° to 85° for 3 1/2 hours. During the reactiontime, about 100 milliliters of water were added to thin the reactionmixture as it thickened upon the cross-linking of the lignosulfonate.The reaction mixture was purified in a manner similar to that describedabove. About 0.5 gram of epoxide was recovered. The cross-linkedlignosulfonate was tested as a flocculating agent. The results anddetails are given in Table I below.

EXAMPLE VIII

In a manner similar to that described in Example VII above, the sodiumbase lignosulfonate was reacted with diglycidyl ether which had anequivalent weight per epoxide of about 73. To 20 grams of the sodiumlignosulfonate, 1.3 grams of diglycidyl ether were added. After thereaction, 0.1 gram of the epoxide was recovered. The product obtainedwas tested as a flocculating agent and the details and results are shownin the table below.

EXAMPLE IX

The sodium base liquor of Example VII was cross-linked with a BisphenolA diglycidyl ether which had an equivalent weight per epoxide of about190. To 20 grams of the sodium lignosulfonate, 3.4 grams of theBisphenol A diglycidyl ether were added. About 0.2 gram of epoxide wasrecovered after the reaction. The product obtained was tested as aflocculating agent and the details and results are given in Table Ibelow.

EXAMPLE X

a. A sodium base spent sulfite liquor was reacted with 1,4-butanedioldiglycidyl ether to cross-link the lignosulfonate in the spent sulfiteliquor. The sodium base spent sulfite liquor was prepared from afermented undialyzed calcium base spent sulfite liquor by reaction withsodium sulfate to precipitate out the calcium sulfate. The sodium baseliquor thus obtained was adjusted to a pH of 11 with sodium hydroxideand then spray dried.

The undialyzed sodium base spent sulfite liquor solids in an amount of20 grams were dissolved in 30 milliliters of water. To the solution,1,4-butanediol diglycidyl ether was added in an amount of 3.5 gramswhich gave a ratio of 1.2 epoxy groups per each phenolic hydroxyl groupof the lignosulfonate. The reaction mixture was reacted for 73 minutesat a temperature of about 90°C during which time 43 milliliters ofadditional water were added. After the reaction, the reaction mixturewas purified in the manner described above. About 0.2 gram of unreactedepoxide was recovered. Based upon the phenolic hydroxyl analysis beforeand after reaction, about 50% of the phenolic hydroxyl had reacted. Thecross-linked lignosulfonate was tested as a flocculating agent and thedetails and results are given in Table I below.

b. In a run similar to that above, a sodium base spent sulfite liquorprepared from a dialyzed calcium base spent sulfite liquor wascross-linked with 1,4 - butanediol diglycidyl ether in an amount whichgave a ratio of 0.86 epoxy group per each phenolic hydroxyl of thelignosulfonate. The reaction was carried out at 90°C for 4 hours. Waterwas periodically added to the reaction mixture to keep the reactionmixture from gelling. The product obtained was cooled, ether extracted,and centrifuged to obtain the reaction product. The product was testedas a flocculating agent at 10 parts per million. The results obtainedand other details are shown in the table below.

c. In a manner similar to Run (b) above, a similar run was made whereinthe 1,4 - butanediol diglycidyl ether was reacted with the sodium baselignosulfonate in a water-dioxane solution in which both thelignosulfonate and di-epoxide were soluble.

Twenty grams of the spent sulfite liquor were dissolved in 25 grams ofdistilled water to which was then added 6 milliliters of 1,4 - dioxane.After the addition of the dioxane, 2.4 grams of the di-epoxide wereadded which gave a ratio of 0.86 grams epoxy group per each phenolichydroxyl group of the lignosulfonate. The reaction mixture was placed onthe steam bath and reacted at a temperature of about 90° for 4 hours.Water was periodically added to the reaction mixture until a total of100 milliliters of additional water had been added. The reactionthickened rapidly and after about a 10 minute reaction time, addition ofwater had to be made every few minutes for about the next 20 minutes inwhich time the 100 milliliters of water were added. After about 30minutes of reaction time, no further additions of water were made butthe reaction continued for an additional 3 1/2 hours. After thereaction, the solution was cooled to room temperature, ether extracted,and centrifuged. Unreacted epoxide in an amount of 0.2 gram wasrecovered from the ether extract. The water solution was evaporatedunder vacuum to remove the remaining ether and tested as a flocculatingagent at 10 parts per million. The results and other details are givenin the table below.

EXAMPLE XI

A sodium base lignosulfonate prepared from a fermented dialyzed calciumbase liquor was reacted with a low molecular weight fraction of adi-epoxide prepared by reacting ethyleneglycol with epichlorohydrin. Thediglycidyl ether had an equivalent weight of 105 per epoxide and wasreacted in an amount of 1.9 grams with 20 grams of the sodiumlignosulfonate in 30 milliliters of water. The mixture was reacted whilebeing stirred at a temperature of about 90°C for 75 minutes. Anadditional amount of water of about 50 milliliters was added during thereaction. Upon purification of the reaction mixture in a manner similarto that described above, about 0.1 gram of the unreacted epoxide wasrecovered. The cross-linked lignosulfonate was tested as a flocculatingagent and the details and results are given in Table I below.

EXAMPLE XII

The sodium lignosulfonate of Example IX was cross-linked with a highermolecular weight fraction of the di-epoxide prepared as described inExample XI above. This fraction had an equivalent weight of 117 ascompared to 105 of the example above. The reaction was carried out inthe manner similar to that of Example XI. The cross-linkedlignosulfonate was tested as a flocculating agent. The results anddetails are given in Table I below.

EXAMPLE XIII

A kraft lignin was cross-linked with 1,4-butanediol diglycidyl ether.The alkali lignin in an amount of 20 grams was dissolved in 50milliliters of water to obtain a solution at pH 8.5. To the solution,7.2 grams of 1,4-butanediol diglycidyl ether were added. The alkalilignin had a phenolic hydroxyl content of about 6% so that the amount ofthe butanediol diglycidyl ether added represented about 0.75 epoxy groupper phenolic hydroxyl of the lignin. The mixture was reacted at atemperature of 85° to 90°C for about 65 minutes. Additional water wasadded periodically during the reaction mixture until a total amount ofabout 100 milliliters had been added.

After the reaction, the reaction mixture was neutralized and extractedwith ether to recover about 0.2 gram of unreacted epoxide from which itwas estimated that about 70% of the phenolic hydroxyl of the lignin hadreacted. The aqueous layer containing the cross-linked lignin was testedas a flocculating agent using the method described above. The resultsare shown in Table I below.

EXAMPLE XIV

A sodium base spent sulfite liquor was reacted with N,N - bis (2,3 -epoxypropyl) dimethylammonium iodide to cross-link the lignosulfonate inthe spent sulfite liquor. The sodium base spent sulfite liquor wasprepared in the manner described above wherein a fermented dialyzedcalcium base liquor was reacted with sodium sulfate to convert the spentsulfite liquor to sodium base be precipitating out the calcium sulfate.The sodium base liquor thus obtained was adjusted to a pH of 11 withsodium hydroxide and then spray dried.

The spray dried sodium base spent sulfite liquor in an amount of 5 gramswas dissolved in 7.5 milliliters of distilled water in a 3-necked roundbottom flask equipped with a condenser. The N,N - bis (2,3 -epoxypropyl) dimethylammonium iodide was added in an amount of 0.75 gramin 4.6 milliliters of water which gave a ratio of 0.86 epoxy group pereach phenolic hydroxyl group on the lignosulfonate. The mixture wasreacted at a reaction temperature of 94°C for about 4 hours. After thereaction had proceeded for about 10 minutes, the viscosity increased tothe extent that an additional 4 milliliters of water was added to dilutethe reaction mixture to permit stirring. A total of 14 milliliters ofwater was thus added periodically in 5 steps. At the end of thereaction, the sample was cooled, blended with additional water, andcentrifuged to obtain approximately 0.2 gram of a water insolubleproduct when dried. The water soluble portion obtained was tested as aflocculating agent at 10 parts per million. The results are shown in thetable below.

In Table I, the flocculating tests were made on the flocculation of clayin an aqueous system. The tests were similar to that described inExample I except that 4,000 parts per million of sodium chloride wereadded to the 4 weight percent clay slurry. The test was performed in themanner described above wherein a 100 milliliter sample of the claysuspension was shaken in a 100 milliliter graduated cylinder and thelength of time for the clay to settle to half volume or the 50milliliter mark on the cylinder was noted and taken as the settlingtime. The flocculating agent was used in an amount of 10 parts permillion and the slurry was at a pH of about 5. The intrinsic viscositieswere determined in a 0.1 N sodium chloride solution.

The results of the above noted products were compared to a blank wherethe clay slurry was settled without the addition of any flocculatingagent and to a second blank to which a dialyzed sodium lignosulfonatewithout being cross-linked was added in an amount of 10 parts permillion.

                                      TABLE I                                     __________________________________________________________________________                  Ratio of                                                                      Epoxy Groups                                                                          Percent of                                                            Per Phenolic                                                                          Phenolic                                                                            Intrinsic                                                                           Settling                                          Di-epoxide                                                                            Hydroxyl of                                                                           Hydroxyls                                                                           Viscosity,                                                                          Time,                                       Example                                                                             Reacted Lignin  Reacted                                                                             dlg.sup.-.sup.1                                                                     Sec.                                        __________________________________________________________________________    IV    Polypropy-                                                                    lene glycol                                                                   diglycidyl                                                                    ether (MW                                                                     per epox-                                                                     ide=190)                                                                              0.85    60    0.13   67                                         V     Polypropy-                                                                    lene glycol                                                                   diglycidyl                                                                    ether (MW                                                                     per epox-                                                                     ide=325)                                                                              0.85    49    0.25  103                                         VI    Polyethy-                                                                     lene glycol                                                                   diglycidyl                                                                    ether (MW                                                                     per epox-                                                                     ide=715)                                                                              1.1     --    --     69                                         VII   1,7-diepoxy-                                                                  octane (MW                                                                    per epox-                                                                     ide=270)                                                                              1.2     --    0.20  102                                         VIII  Diglycidyl                                                                    ether   0.86    70    0.23  104                                         IX    Bisphenol A                                                                   diglycidyl                                                                    ether   0.86    58    0.23  133                                         X (a) Butanediol                                                                    diglycidyl                                                                    ether   1.2     50    --     83                                          (b)          0.86    65    0.33   83                                          (c)          0.86    67    0.27   87                                         XI    Polyethylene                                                                  glycol di-                                                                    glycidyl                                                                      ether (MW                                                                     per epox-                                                                     ide=105)                                                                              0.86    59    0.17  117                                         XII   Polyethylene                                                                  glycol di-                                                                    glycidyl                                                                      ether (MW                                                                     per epox-                                                                     ide=117)                                                                              0.85    61    0.27  100                                         XIII  Butanediol                                                                    diglycidyl                                                                    ether   0.75    70    --    135                                         XIV   N,N-bis(2,3-                                                                  epoxypropyl)                                                                  dimethylammo-                                                                 nium iodide                                                                           0.86    63    0.24  104                                         Blank I       --      --    --    430                                         Blank II                                                                            (dialyzed                                                                     lignosul-                                                                     fonate) --      --    --    450                                         __________________________________________________________________________

What is claimed is:
 1. In a process for the clarification of an aqueoussuspension of solid particle matter wherein a flocculating agent isadded in a sufficient amount to flocculate the suspended particle matterthe improvement which cimprises using as a flocculating agent awater-soluble lignin-di-epoxide reaction product obtained by reacting ata pH in range of 8-13 and a temperature in the range of 50° to 220°C alignin solution containing 20-50 percent lignin with a long-chaineddi-epoxide having a molecular weight in the range of 120 to 1800 to theextent that the phenolic hydroxyl content of the lignin has been reducedfrom 40 to 95%, said di-epoxide having linking atoms selected from thegroup consisting essentially of carbon, nitrogen, sulfur, and oxygen andbeing a terminal di-epoxide with epoxy groups being on the terminal endsof the long chain, said terminal ends being alkylene groups of at least3 carbon atoms.
 2. A process according to claim 1 wherein theflocculating agent is a lignosulfonate-di-epoxide reaction product.
 3. Aprocess according to claim 1 wherein the flocculating agent is an alkalilignin-di-epoxide reaction product.
 4. A process according to claim 1wherein the flocculating agent is obtained by dissolving the lignin inan aqueous medium to form a solution containing from 20 to 50 weightpercent lignin, intermixing the lignin solution at a pH in the range of8 to 13 with the di-epoxide to react the di-epoxide with the lignin. 5.A process according to claim 4 wherein the di-epoxide is selected fromthe group consisting essentially of the following di-epoxides:1.1,2,7,8 - diepoxyoctane; 1,2,11,12 - diepoxydodecane; 1,2,7,8 -diepoxy - 4 - methyloctane; 1,2,7,8 - diepoxy - 4,5 - dimethyloctane;and di-epoxides having a general formula: ##EQU6## Where R representsalkylene radicals having up to 18 carbon atoms, arylene or oxy-linkedarylene radicals having up to 12 carbon atoms and R₁ representshydrogen, phenyl or one or more alkyl radicals such that the totalcarbon atoms of R₁ does not exceed 1/2 of the carbon atoms of the chaincontaining the oxirane groups.
 2. Diglycidyl ethers of 1,4 - butanediol;1,8 - octanediol; 1,12 - dodecanediol; glycerol, sorbitol; Bisphenol A;2,5 - bis (hydroxymethyl) tetrahydrofuran; 1,4 - bis[2-(4'-hydroxyphenyl) ethyl] benzene; and dihydroxynaphthalene; anddi-epoxides of other aromatic and aliphatic polyols having a generalformula: ##EQU7## Where R represents alkylene radicals having up to 18carbon atoms, arylene or oxy-linked arylene radicals having up to 12carbon atoms, and R₁ represents hydrogen, phenyl or one or more alkylradicals such that the total carbon atoms of R₁ is less than 1/2 of thecarbon atoms of the chain containing the oxirane groups.
 3. Diglycidylethers of polyalkylene glycols having a general formula: ##EQU8## Wheren is a positive integer of from 2 to 20, R represents alkylene radicalshaving from 2 to 4 carbon atoms, and R₁ represents hydrogen or alkylradicals having from 1 to 2 carbon atoms with the total of R and R₁ notbeing greater than 4 carbon atoms.
 4. N,N - bis (2,3 - epoxypropyl)methylamine; N,N - bis (2,3 - epoxypropyl) butylmethylammonium iodide;1,4 - butylene-bis [N - (2,3 - epoxypropyl) - N,N - dimethylammoniumiodide] and diglycidyl amines and amine salts having the generalformula: ##EQU9## or ##EQU10## Where "m" is a positive integer of from 2to 5, "n" is a positive integer from 0 to 5, R₁, R₂, R₃, and R₄represent alkyl radicals having from 1 to 2 carbon atoms, and Xrepresents bromide, iodide, arenesulfonate, or acetate ions.
 6. Aprocess according to claim 5 wherein the lignin solution is a solutioncontaining from 30 to 40% lignin and is reacted at a temperature in therange of 75°C to reflux temperature at atmospheric pressure with thedi-epoxide at a pH in the range of 9 to 11 to the extent that thephenolic hydroxyl content of the lignin is reduced by an amount of from50 to 75%.
 7. A process according to claim 6 wherein the lignin is alignosulfonate solution.
 8. A process according to claim 7 wherein thedi-epoxide has a molecular weight in the range of 250 to 800 and is adiglycidyl ether of a polyol.
 9. A process according to claim 8 whereinthe di-epoxide is a diglycidyl ether of a polyalkylene glycol.
 10. Aprocess according to claim 9 wherein the di-epoxide is a diglycidylether of polyethylene glycol.
 11. A process according to claim 6 whereinthe lignin is an alkali lignin and the di-epoxide is a diglycidyl etherof polyethylene glycol.